Identidy visible points on an arbitrary global hemishpere view.

Given a global hemispheric field of view defined by a single latitudinal and longitudinal centroid focal point, project geographic points onto the hemishpere.

project_to_hemisphere(lon, lat, lon0, lat0)

Arguments

lon	vector of longitudes.
lat	vector of latitudes.
lon0	longitude of focus coordinates.
lat0	latitude of focus coordinates.

Value

returns a data frame.

Details

project_to_hemisphere identifies whether each pair of coordinates in the lat and lon vectors is in a field of view defined by a centroid focal point (lat0, lon0) and returns a data frame containing the original coordinates and a column indicating if the coordinates are in the field of view (TRUE or FALSE).

Examples

lon <- seq(-180, 180, length.out=60)
lat <- rep(seq(-90, 90, length.out=30), 2)
project_to_hemisphere(lon, lat , 0, 0)
#> # A tibble: 60 x 3
#>      lon   lat inview
#>    <dbl> <dbl> <lgl> 
#>  1 -180  -90   FALSE 
#>  2 -174. -83.8 FALSE 
#>  3 -168. -77.6 FALSE 
#>  4 -162. -71.4 FALSE 
#>  5 -156. -65.2 FALSE 
#>  6 -149. -59.0 FALSE 
#>  7 -143. -52.8 FALSE 
#>  8 -137. -46.6 FALSE 
#>  9 -131. -40.3 FALSE 
#> 10 -125. -34.1 FALSE 
#> # ... with 50 more rows